Surgical forceps including thermal spread control

ABSTRACT

A surgical instrument includes one or more electrically-conductive plates adapted to connect to a source of energy for supplying energy to tissue to treat tissue, a temperature sensing element, and a thermal spread control assembly coupled to the temperature sensing element. The thermal spread control assembly is configured to determine a flow rate of heat energy across the temperature sensing element and to control the energy applied to the electrically-conductive plate and/or control active cooling of the temperature sensing element in accordance with the determined flow rate of heat energy.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application Ser. No. 61/865,467, filed on Aug. 13, 2013, theentire contents of which are incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to surgical devices and, moreparticularly, to surgical forceps and end effector assemblies thereoffor controlling thermal spread during energy-based tissue treatmentand/or energy-based tissue cutting.

Background of Related Art

A surgical forceps is a plier-like device which relies on mechanicalaction between its jaws to grasp, clamp, and constrict tissue.Energy-based surgical forceps utilize both mechanical clamping actionand energy to affect hemostasis by heating tissue to coagulate and/orcauterize tissue. Certain surgical procedures require more than simplycauterizing tissue and rely on the unique combination of clampingpressure, precise energy control and gap distance (i.e., distancebetween opposing jaw members when closed about tissue) to “seal” tissue.Typically, once tissue is sealed, the surgeon has to accurately severthe tissue along the newly formed tissue seal. Accordingly, many tissuesealing devices have been designed which incorporate a knife or blademember which effectively severs the tissue after forming a tissue seal.More recently, tissue sealing devices have incorporated energy-basedcutting features for energy-based tissue division.

SUMMARY

As used herein, the term “distal” refers to the portion that is beingdescribed which is further from a user, while the term “proximal” refersto the portion that is being described which is closer to a user.Further, to the extent consistent, any of the aspects described hereinmay be used in conjunction with any or all of the other aspectsdescribed herein.

In accordance with the present disclosure, a surgical instrument isprovided. The surgical instrument includes one or moreelectrically-conductive plates adapted to connect to a source of energyfor supplying energy to tissue to treat tissue, a temperature sensingelement, and a thermal spread control assembly coupled to thetemperature sensing element. The thermal spread control assembly isconfigured to determine a flow rate of heat energy across thetemperature sensing element and to control the energy applied to theelectrically-conductive plate and/or control active cooling of thetemperature sensing element in accordance with the determined flow rateof heat energy.

In aspects, the temperature sensing element is incorporated into theelectrically-conductive plate. Alternatively, the temperature sensingelement may be disposed about an outer periphery of theelectrically-conductive plate.

In aspects, a thermoelectric cooler is coupled to the temperaturesensing element for actively cooling the temperature sensing element.The thermal spread control assembly may be configured to control powersupplied to the thermoelectric cooler to vary an amount of coolingprovided by the thermal spread control assembly. Further, athermally-conductive, electrically insulative material may be disposedbetween the thermoelectric cooler and the temperature sensing element.

In aspects, the thermal spread control assembly is configured to measurea temperature at each of a first side and a second side of thetemperature sensing element to determine a temperature differentialtherebetween. Further, the thermal spread control assembly may beconfigured to determine the flow rate of heat energy across thetemperature sensing element in accordance with the temperaturedifferential and a thermal conductivity of the temperature sensingelement.

In aspects, the electrically-conductive plate and the temperaturesensing element are disposed within an end effector assembly of thesurgical instrument. The thermal spread control assembly may likewise bedisposed within the end effector assembly, or may be remotely positionedrelative to the end effector assembly.

In aspects, the thermal spread control assembly performs control inaccordance with the determined flow rate of heat energy to maintain theflow rate of heat energy within a predetermined range. Alternatively,the thermal spread control assembly may be configured to perform controlin accordance with the determined flow rate of heat energy to maintainthe flow rate of heat energy below a predetermined threshold.

In accordance with the present disclosure, a method of treating tissueis provided including applying energy to tissue, determining a flow rateof heat energy across a temperature sensing element, and controlling theenergy applied to tissue and/or controlling active cooling of tissuebased upon the flow rate of heat energy.

In aspects, applying energy to tissue includes grasping tissue betweenfirst and second electrically-conductive plates and conducting energytherebetween. In such aspects, determining the flow rate of heat energyacross the temperature sensing element may include determining the flowrate of heat energy across the first and/or secondelectrically-conductive plates. Alternatively, determining the flow rateof heat energy across the temperature sensing element may includedetermining the flow rate of heat energy across at temperature sensingelectrode disposed about an outer periphery the first and/or secondelectrically-conductive plates.

In aspects, the flow rate of heat energy across the temperature sensingelement is determined in accordance with a temperature differentialbetween first and second sides of the temperature sensing element and athermal conductivity of the temperature sensing element.

In aspects, controlling active cooling of tissue based upon the flowrate of heat energy includes selectively applying power to athermoelectric cooler.

In aspects, both the energy applied to tissue and active cooling oftissue are controlled based upon the flow rate of heat energy.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the present disclosure are describedherein with reference to the drawings wherein:

FIG. 1 is a front, side, perspective view of an endoscopic surgicalforceps configured for use in accordance with the present disclosure;

FIG. 2 is a front, side, perspective view of an open surgical forcepsconfigured for use in accordance with the present disclosure;

FIG. 3A is a front, side, perspective view of an end effector assemblyconfigured for use with the forceps of FIG. 1 or 2;

FIG. 3B is a transverse, cross-sectional view of the end effectorassembly of FIG. 3A;

FIG. 4 is a transverse, cross-sectional view of another end effectorassembly configured for use with the forceps of FIG. 1 or 2;

FIG. 5A is a transverse, cross-sectional view of an end effectorassembly provided in accordance with the present disclosureincorporating a thermal spread control assembly;

FIG. 5B is a longitudinal, cross-sectional view of the end effectorassembly of FIG. 5A;

FIG. 6 is an enlarged, schematic illustration of the area of detailindicated as “6” in FIG. 5A;

FIG. 7A is a transverse, cross-sectional view of a jaw member of an endeffector assembly provided in accordance with the present disclosureincorporating another thermal spread control assembly

FIG. 7B is a top view of the jaw member of FIG. 7A; and

FIG. 8 is a transverse, cross-sectional view of a jaw member of an endeffector assembly provided in accordance with the present disclosureincorporating another thermal spread control assembly.

DETAILED DESCRIPTION

Turning to FIGS. 1 and 2, FIG. 1 depicts a forceps 10 for use inconnection with endoscopic surgical procedures and FIG. 2 depicts anopen forceps 10′ contemplated for use in connection with traditionalopen surgical procedures. For the purposes herein, either an endoscopicdevice, e.g., forceps 10, an open device, e.g., forceps 10′, or anyother suitable surgical device may be utilized in accordance with thepresent disclosure. Obviously, different electrical and mechanicalconnections and considerations apply to each particular type of device,however, the aspects and features of the present disclosure remaingenerally consistent regardless of the particular device used.

Referring to FIG. 1, an endoscopic forceps 10 is provided defining alongitudinal axis “X” and including a housing 20, a handle assembly 30,a rotating assembly 70, an activation assembly 80, and an end effectorassembly 100. Forceps 10 further includes a shaft 12 having a distal end14 configured to mechanically engage end effector assembly 100 and aproximal end 16 that mechanically engages housing 20. A cable 8 connectsforceps 10 to an energy source, e.g., generator “G,” although forceps 10may alternatively be configured as a battery-powered device. Cable 8includes a wire (or wires) (not shown) extending therethrough that hassufficient length to extend through shaft 12 in order to provide energyto at least one of tissue-contacting plates 114, 124 (FIG. 3A) of jawmembers 110, 120, respectively, as well as to energy-based cuttingmember 130 (FIG. 3A) of jaw member 120. Activation assembly 80 includesa two-mode activation switch 82 provided on housing 20 for selectivelysupplying energy to jaw members 110, 120 for treating, e.g., sealing,tissue (the first mode), and for energy-based tissue cutting (the secondmode).

Handle assembly 30 includes a fixed handle 50 and a movable handle 40.Fixed handle 50 is integrally associated with housing 20 and handle 40is movable relative to fixed handle 50. Movable handle 40 of handleassembly 30 is operably coupled to a drive assembly (not shown) that,together, mechanically cooperate to impart movement of jaw members 110,120 between a spaced-apart position and an approximated position tograsp tissue between jaw members 110, 120. More specifically, as shownin FIG. 1, movable handle 40 is initially spaced-apart from fixed handle50 and, correspondingly, jaw members 110, 120 are disposed in thespaced-apart position. Movable handle 40 is depressible from thisinitial position to a depressed position corresponding to theapproximated position of jaw members 110, 120. Rotating assembly 70 isrotatable in either direction about longitudinal axis “X” to rotate endeffector 100 about longitudinal axis “X.”

Referring to FIG. 2, an open forceps 10′ is shown including twoelongated shaft members 12 a, 12 b, each having a proximal end 16 a, 16b, and a distal end 14 a, 14 b, respectively. Forceps 10′ is configuredfor use with an end effector assembly 100′ similar to end effectorassembly 100 (FIG. 1). More specifically, end effector assembly 100′includes first and second jaw members 110′, 120′ attached to respectivedistal ends 14 a, 14 b of shaft members 12 a, 12 b. Jaw members 110′,120′ are pivotably connected about a pivot 103′. Each shaft member 12 a,12 b includes a handle 17 a, 17 b disposed at the proximal end 16 a, 16b thereof. Each handle 17 a, 17 b defines a finger hole 18 a, 18 btherethrough for receiving a finger of the user. As can be appreciated,finger holes 18 a, 18 b facilitate movement of shaft members 12 a, 12 brelative to one another to, in turn, pivot jaw members 110′, 120′ froman open position, wherein jaw members 110′, 120′ are disposed inspaced-apart relation relative to one another, to a closed position,wherein jaw members 110′, 120′ cooperate to grasp tissue therebetween.

One of the shaft members 12 a, 12 b of forceps 10′, e.g., shaft member12 a, includes a proximal shaft connector 19 configured to connect theforceps 10′ to generator “G” (FIG. 1). Proximal shaft connector 19secures a cable 8′ to forceps 10′ such that the user may selectivelysupply energy, e.g., electrosurgical energy, to jaw members 110′, 120′for treating, e.g., sealing, tissue and for energy-based tissue cutting.More specifically, a first activation assembly 80′ is provided forsupplying energy to jaw members 110′, 120′ to treat tissue uponsufficient approximation of shaft members 12 a, 12 b, e.g., uponactivation of activation button 82′ via shaft member 12 a. A secondactivation assembly 84 including a selectively depressible activationbutton 86 is provided one of the shaft members 12 a, 12 b, e.g., shaftmember 12 b, for selectively supplying energy, e.g., electrosurgicalenergy, to either or both of jaw members 110′, 120′ for energy-basedtissue cutting.

With reference to FIGS. 3A and 3B, end effector assembly 100 of forceps10 (FIG. 1) is shown, although end effector assembly 100′ may similarlybe used in conjunction with forceps 10′ (FIG. 2), or any other suitablesurgical device. For purposes of simplicity, end effector assembly 100is described herein as configured for use with forceps 10 (FIG. 1).

Each jaw member 110, 120 of end effector assembly 100 includes aproximal flange portion 111 a, 121 a, a distal jaw portion 111 b, 121 b,an outer insulative jaw housing 112, 122, and a tissue-contacting plate114, 124, respectively. Proximal flange portions 111 a, 121 a of jawmembers 110, 120 are pivotably coupled to one another about pivot 103for moving jaw members 110, 120 between the spaced-apart andapproximated positions. Distal jaw portions 111 b, 121 b of jaw members110, 120 are configured to support jaw housings 112, 122, andtissue-contacting plates 114, 124, respectively, thereon. Further, oneof the jaw members 110, 120, e.g., jaw members 120, includes anenergy-based cutting member 130 disposed thereon.

Tissue-contacting plates 114, 124 are formed from an electricallyconductive material, e.g., for conducting electrical energy therebetweenfor treating tissue, although tissue-contacting plates 114, 124 mayalternatively be configured to conduct any suitable energy throughtissue grasped therebetween for energy-based tissue treatment, e.g.,tissue sealing. Energy-based cutting member 130 is likewise formed froman electrically conductive material, e.g., for conducting electricalenergy between energy-based cutting member 130 and one or both oftissue-contacting plates 114, 124 for electrically cutting tissue,although energy-based cutting member 130 may alternatively be configuredto conduct any suitable energy through tissue for electrically cuttingtissue.

Tissue-contacting plates 114, 124 are coupled to activation switch 82(FIG. 1) and generator “G” (FIG. 1) or other suitable source of energy,e.g., via the wires (not shown) extending from cable 8 (FIG. 1) throughforceps 10 (FIG. 1), such that energy, e.g., electrosurgical energy, maybe selectively supplied to tissue-contacting plate 114 and/ortissue-contacting plate 124 and conducted therebetween and throughtissue disposed between jaw members 110, 120 to treat, e.g., seal,tissue in a first mode of operation. Likewise, cutting member 130 issimilarly coupled to activation switch 82 (FIG. 1) and generator “G”(FIG. 1) such that energy, e.g., electrosurgical energy, may beselectively supplied to cutting member 130 and conducted through tissuedisposed between jaw members 110, 120 to either or both oftissue-contacting plates 114, 124 to cut tissue in a second mode ofoperation. A first insulating member 150 surrounds cutting member 130 toinsulate tissue-contacting plate 124 and cutting member 130 from oneanother. A second insulating member 160 disposed within a longitudinalslot defined within tissue-contacting plate 114 of jaw member 110opposes cutting member 130 to insulate cutting member 130 fromtissue-contacting plate 114 of jaw member 110 when jaw members 110, 120are disposed in the approximated position.

Turning to FIG. 4, another embodiment of an end effector assemblyconfigured for use with either forceps 10 (FIG. 1) or forceps 10′ (FIG.2) is shown generally identified by reference numeral 200. End effectorassembly 200 is similar to end effector assembly 100 (FIGS. 3A-3B) and,thus, only the differences therebetween will be described in detailbelow for purposes of brevity.

End effector assembly 200 includes first and second jaw members 210,220, each including a tissue-contacting plate 214, 224 and alongitudinally-extending slot 216, 226, respectively. A cutting member230 is configured for longitudinal translation through slots 216, 226 ofjaw members 210, 220, e.g., upon activation of a trigger (not shown)operably coupled to cutting member 230, to cut mechanically tissuegrasped between jaw members 210, 220. Cutting member 230 may beconfigured for mechanical cutting, or may be energizable, e.g., viaelectrical coupling to generator “G” (FIG. 1) via the one or more wires(not shown) of cable 8 (FIG. 1), for electro-mechanically cuttingtissue.

Turning now to FIGS. 5A-6, one embodiment of an end effector assembly,similar to end effector assemblies 100, 200 (FIGS. 3A-3B and 4,respectively), and configured for use with forceps 10 (FIG. 1), forceps10′ (FIG. 2), or any other suitable surgical instrument, is showngenerally designated by reference numeral 300. As will be described ingreater detail below, end effector assembly 300 is configured to providethermal spread control during tissue treatment, e.g., tissue sealing,and, in embodiments where electrical tissue cutting is provided (seeFIGS. 3A-3B), to likewise provide thermal spread control during tissuecutting.

End effector assembly 300 includes first and second jaw members 310,320, each including an outer jaw housing 312, 322 and atissue-contacting plate 314, 324, respectively, disposed thereon. Endeffector assembly 300 further includes a thermal spread control assembly315, 325 embedded within either or both of jaw members 310, 320,although thermal spread control assemblies 315, 325 (or a single thermalspread control assembly) may alternatively be disposed within a remoteportion of the surgical instrument, e.g., housing 20 (FIG. 1), or withinan external energy source, e.g., generator “G” (FIG. 1). End effectorassembly 300 may also include any or all of the features of end effectorassemblies 100, 200 (FIGS. 3A-3B and 4, respectively), described above.However, such features will not be described hereinbelow for purposes ofbrevity.

Continuing with reference to FIGS. 5A-6, jaw members 310, 320 aremovable relative to one another from a spaced-apart position to anapproximated position for grasping tissue between tissue-contactingplates 314, 324. Tissue-contacting plates 314, 324, similarly asdescribed above, are coupled to generator “G” (FIG. 1) or other suitablesource of energy such that energy, e.g., electrosurgical energy, may beselectively supplied to tissue-contacting plate 314 and/ortissue-contacting plate 324 and conducted therebetween and throughtissue disposed between jaw members 310, 320 to treat, e.g., seal,tissue.

Tissue-contacting plates 314, 324 of jaw members 310, 320, respectively,each include first and second sides 314 a, 324 a and 314 b, 324 b,respectively. First sides 314 a, 324 a of tissue-contacting plates 314,324, respectively, are positioned to oppose one another and areconfigured to grasp tissue therebetween. Second sides 314 b, 324 b oftissue-contacting plates 314, 324, on the other hand, are positionedadjacent respective outer jaw housings 312, 322, respectively.Tissue-contacting plates 314, 324, in addition to being configured asenergizable electrodes for treating tissue, as described above, are alsoconfigured as temperature-sensing electrodes, as will be described ingreater detail below.

Jaw members 310, 320 each further include a cooling element 316, 326,e.g., a thermoelectric or Peltier cooler, disposed adjacent respectivetissue-contacting plates 314, 324. More specifically, cooling elements316, 326 are positioned adjacent second sides 314 b, 324 b oftissue-contacting plates 314, 324, respectively, so as to not interferewith the grasping of tissue between first sides 314 a, 324 a oftissue-contacting plates 314, 324, respectively, and are dimensionedsimilarly to tissue-contacting plates 314, 324 to substantially extendacross the respective second sides 314 b, 324 b thereof. Coolingelements 316, 326 may be coupled to power sources 332, 334, e.g.,batteries, of thermal spread control assemblies 315, 325, respectively,for powering cooling elements 316, 326, although cooling elements 316,326 may alternatively be coupled to generator “G” (FIG. 6) for thispurpose.

A thermally-conductive, electrically-insulative pad 318, 328 is disposedbetween each of tissue-contacting plates 314, 324 and its respectivecooling element 316, 326. As can be appreciated, pads 318, 328electrically-insulate tissue-contacting plates 314, 324 from coolingelements 316, 326, respectively, but permit thermal conductiontherebetween, thus allowing for cooling elements 316, 326 to selectivelycool tissue-contacting plates 314, 324, as will be described in greaterdetail below.

Referring still to FIGS. 5A-6, and to FIG. 6 in particular,tissue-contacting plates 314, 324, in conjunction with cooling elements316, 326, provide active thermal spread control for minimizing thermalspread to tissue disposed outside of jaw members 310, 320 during tissuetreatment (and/or electrical tissue cutting), e.g., during applicationof energy to tissue grasped between jaw members 310, 320. Morespecifically, as will be described in greater detail below, thermalspread control assemblies 315, 325 are coupled to both tissue-contactingplates 314, 324 and cooling elements 316, 326 to provide tissue-sitefeedback-based control of the energy supplied to tissue-contactingplates 314, 324 and/or the power supplied to cooling elements 316, 326so as to minimize thermal spread outside of the treatment area, e.g.,outside of jaw members 310, 320.

Thermal spread control assemblies 315, 325 include sensing circuits 330,340 coupled to the respective tissue-contacting plates 314, 324 formeasuring the temperature differential ΔT_(A)=T_(A1)−T_(A2),ΔT_(B)=T_(B1)−T_(B2) between the respective first and second sides 314a, 324 a and 314 b, 324 b of tissue-contacting plates 314, 324. Basedupon the temperature differentials ΔT_(A), ΔT_(B), and given a knownthermal conductivity, K, for tissue-contacting plates 314, 324, the flowrate of heat energy, Q, through each tissue-contacting plate 314, 324,can be determined in accordance with:

${Q = {\kappa \; A\frac{\Delta \; T}{d}}},$

where: “κ” is the thermal conductivity, W/m*κ, “Q” is the rate of heatflow, W, “A” is the contact area, “d” is the distance of heat flow, and“ΔT” is the temperature difference.

In addition to measuring the temperature differentials ΔT_(A), ΔT_(B),monitoring the temperatures T_(A1), T_(B1) at first sides 314 a, 324 aof tissue-contacting plates 314, 324, respectively, provides a measureof the tissue treatment temperature (T_(tt)) as a function of theapplied energy. Controlling the tissue treatment temperature (T_(tt)),in conjunction with thermal spread control with applied tissue treatmentenergy, simultaneously provides controlled tissue treatment efficacy.Tissue temperature control provides another means of thermal spreadcontrol through the monitored tissue temperatures T_(A1), T_(B1) atfirst sides 314 a, 324 a of tissue-contacting plates 314, 324,respectively. Note that the tissue treatment temperature as a functionof time, T_(tt)/dt=T_(A1)/dt or T_(B1)/dt, when monitored, can beutilized to control the tissue treatment temperature rate of change.Monitoring the tissue temperature difference T_(A1)−T_(B1) between thefirst sides 314 a, 324 a of tissue-contacting plates 314, 324, providesa uniformity measure of thermal tissue heating and/or a tissuetemperature gradient with applied treatment energy.

Sensing circuits 330, 340 are further configured to measure the voltagesV_(A), V_(B) across tissue-contacting plates 314, 324. Based upon aknown electrode resistivity (φ for tissue contacting plates 314, 324, asexpressed by electrode resistance R(Ω), a measure of thetissue-delivered RF current (I) passing through the treatment tissue asmonitored by V_(A) and V_(B) can be determined in accordance with:

${{R(\Omega)} = \frac{\rho \; l}{A}},$

where “R” is the electrode resistance, “ρ” is the electrode resistivity,“I” is the electrode length, and “A” is the electrode area. Thus, thetissue-delivered RF current can be measured at either tissue-contactingplates 314, 324 according to:

${{RFCurrent}(I)} = {\frac{V_{A}}{\left\lbrack {{R(\Omega)},314} \right\rbrack} = {\frac{V_{B}}{\left\lbrack {{R(\Omega)},324} \right\rbrack}.}}$

Accordingly, and as will be described in greater detail below, using theflow rate of heat, Q, through tissue-contacting plates 314, 324, thermalspread control assemblies 315, 325 can control the energy (a function ofV_(A), V_(B), ΔT_(A), ΔT_(B), T_(A1), and T_(B1)) by monitoringtissue-contacting plates 314, 324 and/or the power supplied to coolingelements 316, 326 (via power sources 332, 334) for actively coolingtissue-contacting plates 314, 324, to minimize thermal spread.

Continuing with particular reference to FIG. 6, as mentioned above,sensing circuits 330, 340 of thermal spread control assemblies 315, 325,respectively, are configured to measure the temperature differentialsΔT_(A), ΔT_(B) between the first and second sides 314 a, 324 a and 314b, 324 b of tissue-contacting plates 314, 324 and the voltages V_(A),V_(B) across tissue-contacting plates 314, 324, respectively. Thissensed data is transmitted to controllers 342, 344 of thermal spreadcontrol assemblies 315, 325, which calculate the flow rate of heatenergy, Q, through respective tissue-contacting plates 314, 324, andcontrol the energy, e.g., voltages V_(A), V_(B), supplied totissue-contacting plates 314, 324, as well as the power supplied tocooling elements 316, 326 in accordance therewith.

It has been found that an increased flow rate of heat energy, Q, throughtissue-contacting plates 314, 324 is an indication of increased thermalspread, or an increased potential of thermal spread. Accordingly,controllers 342, 344 may be configured such that, when the flow rate ofheat energy, Q, across either or both tissue-contacting plates 314, 324exceeds a pre-determined threshold, controllers 342, 344 direct powersources 332, 334 to increase the supply of power to cooling elements316, 326 and/or reduce the energy supplied to tissue-contacting plates314, 324, e.g., reduce voltages V_(A), V_(B) or the gradienttherebetween. Increasing the power supplied to cooling elements 316, 326enhances the cooling effect of cooling elements 316, 326, therebyincreasing the cooling of tissue-contacting plates 314, 324 and, thus,the cooling of tissue adjacent thereto. Reducing the supply of energy totissue-contacting plates 314, 324 reduces the amount of energy conductedthrough tissue grasped therebetween and, thus, reduces the heating oftissue. As can be appreciated, each of these has the effect of reducingthermal spread.

As detailed above, controllers 342, 344, based on the sensed datareceived from sensing circuits 330, 340, control the supply of power tocooling elements 316, 326 and/or the energy supplied totissue-contacting plates 314, 324, in order to control thermal spread.More specifically, controllers 342, 344 may be configured to maintainthe flow rate of heat energy, Q, below a pre-determined threshold, orwithin a pre-determined range via the tissue-site feedback-based controlloop described above. The particular threshold or range may be set incontrollers 342, 344, adjustable via a user (using generator “G” (FIG.1), or may be automatically determined by controllers 342, 344 basedupon sensed conditions, e.g., tissue impedance, distance betweentissue-contacting plates 314, 324, grasping pressure applied to tissuebetween tissue-contacting plates 314, 324, etc.

Turning now to FIGS. 7A-7B, another embodiment of an end effectorassembly (with one of the jaw members removed) provided in accordancewith the present disclosure and configured to provide thermal spreadcontrol during application of energy to tissue is shown generallydesignated by reference numeral 400. End effector assembly 400 issimilar to end effector assembly 300 (FIGS. 5A-6) and, thus, only thedifferences therebetween will be described in detail below for purposesof brevity. Further, the jaw members of end effector assembly 400 aresimilar to one another and, thus, only jaw member 420 is shown in thedrawings and described below.

With continued reference to FIGS. 7A-7B, jaw member 420 includes anouter jaw housing 422 and a tissue-contacting plate 424, respectively,disposed thereon. A thermal spread control assembly 425 is embeddedwithin jaw member 420, although thermal spread control assembly 425 mayalternatively be remotely disposed. Tissue-contacting plate 424, iscoupled to generator “G” (FIG. 1) or other suitable source of energysuch for conducting energy through tissue to treat, e.g., seal, tissue.Tissue-contacting plate 424 defines an outer periphery 429.

Jaw member 420 further include a thermal sensing electrode 450 disposedon jaw housing 422. Thermal sensing 450 electrode is spaced-apart fromand disposed about the outer periphery 429 of tissue-contacting plate424. Thermal sensing electrode 450 is generally co-planar withtissue-contacting plate 424. A cooling element 456, e.g., athermoelectric or Peltier cooler, is disposed adjacent thermal sensingelectrode 450 on the jaw member side thereof, similarly as describedabove with respect to tissue-contacting plates 314, 324 and coolingelements 316, 326, respectively (see FIGS. 5A-6). Further, athermally-conductive, electrically-insulative pad 458 is disposedbetween thermal sensing electrode 450 and cooling element 456 toelectrically-insulate thermal sensing electrode 450 and cooling element456 from one another while permitting thermal conduction therebetween,thus allowing for cooling element 456 to selectively cool thermalsensing electrode 450, thereby controlling thermal spread beyond endeffector assembly 400.

Referring still to FIGS. 7A-7B, thermal sensing electrode 450 andcooling element 456 provide active thermal spread control for minimizingthermal spread to tissue disposed outside of end effector assembly 400during tissue treatment (and/or electrical tissue cutting). Morespecifically, a thermal spread control assembly 425 is coupled to boththermal sensing electrode 450 and cooling element 456 to providetissue-site feedback-based control of the energy supplied totissue-contacting plate 424 and/or the power supplied to cooling element456 so as to minimize thermal spread outside of the treatment area,e.g., outside of end effector assembly. Thermal spread assembly 425 maybe configured for use with thermal sensing electrode 450 and coolingelement 456 similarly as described above with respect to thermal spreadassemblies 315, 325 use with tissue-contacting surfaces 314, 324 andcooling elements 316, 326, (FIGS. 5A-6).

With reference to FIG. 8, another embodiment of an end effector assembly(with one of the jaw members removed) provided in accordance with thepresent disclosure and configured to provide thermal spread controlduring application of energy to tissue is shown generally designated byreference numeral 500. End effector assembly 500 is similar to endeffector assembly 400 (FIGS. 7A-7B) and, thus, only the differencestherebetween will be described in detail below for purposes of brevity.Further, the jaw members of end effector assembly 500 are similar to oneanother and, thus, only jaw member 520 is shown in the drawings anddescribed below.

Jaw member 520 of end effector assembly 500 is similar to jaw member 420(FIGS. 7A-7B), except that, rather than providing active cooling tocontrol thermal spread, e.g., using a thermoelectric or Peltier cooler,jaw member 520 provides for passive cooling. Jaw member 520 includes anouter jaw housing 522 and a tissue-contacting plate 524, respectively,disposed thereon. Tissue-contacting plate 524, is coupled to generator“G” (FIG. 1) or other suitable source of energy such for conductingenergy through tissue to treat, e.g., seal, tissue. Tissue-contactingplate 524 defines an outer periphery 529.

Jaw member 520 further includes a thermal sensing electrode 550 disposedon jaw housing 522. Thermal sensing electrode 550 is spaced-apart fromand disposed about the outer periphery 529 of tissue-contacting plate524. Thermal sensing electrode 550 is configured to passively absorbheat from tissue adjacent thereto to reduce thermal spread beyond endeffector assembly 500. Thermal sensing electrode 550 is also coupled toa thermal spread control assembly 525 that, similarly as described abovewith respect to previous embodiments, provides tissue-sitefeedback-based control of the energy supplied to tissue-contacting plate524 based upon the flow rate of heat energy, Q, across thermal sensingelectrode 550, so as to minimize thermal spread outside of the treatmentarea, e.g., outside of end effector assembly.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. While several embodiments of the disclosure have been shownin the drawings, it is not intended that the disclosure be limitedthereto, as it is intended that the disclosure be as broad in scope asthe art will allow and that the specification be read likewise.Therefore, the above description should not be construed as limiting,but merely as exemplifications of particular embodiments. Those skilledin the art will envision other modifications within the scope and spiritof the claims appended hereto.

1-20. (canceled)
 21. A surgical instrument, comprising: an electrodedefining a first side and a second side, the electrode adapted toconnect to a source of energy for supplying energy to tissue to treattissue; at least one temperature sensor associated with the firstelectrode, the at least one temperature sensor configured to sense afirst temperature adjacent the first side of the electrode and a secondtemperature adjacent the second side of the electrode; and a controllercoupled to the temperature sensor, the controller configured todetermine a flow rate of heat energy across the first electrode based atleast in part on the first temperature and the second temperature. 22.The surgical instrument according to claim 21, wherein the controller isconfigured to control the energy applied to the electrode in accordancewith the determined flow rate of heat energy.
 23. The surgicalinstrument according to claim 22, wherein the controller is configuredconfigured to control the energy applied to the electrode in accordancewith the determined flow rate of heat energy to maintain the flow rateof heat energy within a range.
 24. The surgical instrument according toclaim 22, wherein the controller is configured configured to control theenergy applied to the electrode in accordance with the determined flowrate of heat energy to maintain the flow rate of heat energy below athreshold.
 25. The surgical instrument according to claim 21, whereinthe controller is configured to control active cooling of the electrodein accordance with the determined flow rate of heat energy.
 26. Thesurgical instrument according to claim 25, wherein the controller isconfigured configured to control the active cooling of the electrode inaccordance with the determined flow rate of heat energy to maintain theflow rate of heat energy within a range.
 27. The surgical instrumentaccording to claim 25, wherein the controller is configured configuredto control the active cooling of the electrode in accordance with thedetermined flow rate of heat energy to maintain the flow rate of heatenergy below a threshold.
 28. The surgical instrument according to claim25, further comprising a thermoelectric cooler operably coupled to theelectrode, wherein the thermoelectric cooler is configured to activelycool the electrode, and wherein the controller is configured to controlthe thermoelectric cooler.
 29. The surgical instrument according toclaim 21, wherein the controller is configured to determine the flowrate of heat energy across the electrode in accordance with the firstand second temperatures and a thermal conductivity of the electrode. 30.A method of treating tissue, comprising: applying energy from anelectrode to tissue, the electrode having a first side and a secondside; determining a first temperature adjacent the first side of theelectrode; determining a second temperature adjacent the second side ofthe electrode; and determining a rate of flow of heat energy across theelectrode based at least in part on the first temperature and the secondtemperature.
 31. The method according to claim 30, further comprisingcontrolling a supply of energy to the electrode based upon thedetermined flow rate of heat energy.
 32. The method according to claim31, further comprising controlling the supply of energy to the electrodebased upon the determined flow rate of heat energy to maintain the flowrate of heat energy within a range.
 33. The method according to claim31, further comprising controlling the supply of energy to the electrodebased upon the determined flow rate of heat energy to maintain the flowrate of heat energy below a threshold.
 34. The method according to claim31, further comprising controlling active cooling of the electrode inaccordance with the determined flow rate of heat energy.
 35. The methodaccording to claim 34, further comprising controlling the active coolingof the electrode in accordance with the determined flow rate of heatenergy to maintain the flow rate of heat energy within a range.
 36. Themethod according to claim 34, further comprising controlling the activecooling of the electrode in accordance with the determined flow rate ofheat energy to maintain the flow rate of heat energy below a threshold.37. The method according to claim 31, wherein the flow rate of heatenergy across the electrode is determined in accordance with the firstand second temperatures and a thermal conductivity of the electrode.